The invention concerns an apparatus and method for drawing looped yarn from a conveyor belt.
It is known from German Patent 27 47 368 to pass a conveyor belt through a yarn treating chamber upon which the yarn is located in the form of a hollow cylinder of ordered loops. After the looped yarn has been treated in the chamber the loops are unravelled, and the yarn is drawn from the conveyor belt and wound onto a spool. The rate of yarn removal is a function of the rate at which the looped yarn is deposited onto the conveyor belt and of the shrinkage of the yarn during the heat treatment. A photoelectric cell is located at the outlet of the yarn treating chamber to detect the position of the terminal loops prior to their removal from the conveyor belt and regulate the rate at which the yarn is drawn off the belt in accordance with that detected position.
It is further known in such an apparatus to provide a holding device to keep the loops pressed flat on the conveyor belt prior to their removal. This device is in the form of a stationary trough, which defines the draw-off point of the yarn from the conveyor belt. The yarn is drawn off at said draw-off point initially essentially parallel to the conveyor belt.
If the operation of the drawing-off device, which for example may be a spooling frame, is interrupted, for example when the spooling frame must be temporarily deactivated to replace a receiving spool, more loops than normal accumulate on the conveyor belt and move downstream of the holding device. The photoelectric cell correlated with the draw-off point is ineffective in such a case, as it is no longer able to detect the end of the loops. The holding device no longer cooperates with the last loop. This can lead to difficulties upon the reactivation of the draw-off mechanism, as the loops located on the conveyor belt may be opened up (drawn off) without being held flat against the conveyor belt. This could interfere with the draw-off process.
It is an object of the invention to provide an apparatus and method of the aforementioned type so that the yarn is removed from the conveyor belt without difficulty even if the operation of the drawing device is interrupted.